Typing of influenza B viruses HA1 gene by RT-PCR-SSCP

  Objective   To screen the influenza B viruses mutation within the amplified region which included the high-mutable site by RT-PCR-SSCP, and to study the characteristics of HA1 gene of influenza B viruses isolated from 2001 to 2004 in Tianjin.

  Methods   Viral RNA was used for RT-PCR to amplify the high-mutable region of 308bp, then was classified by SSCP.The purified PCR products of representative strains were sequenced.The data obtained were analysed with the software DNASTAR.

  Results   Influenza B viruses isolated in Tianjin in recent years were classified into five sorts by SSCP.Victoria-lineage strains compared with B/Hongkong/330/2001 had six mutation points in antigenic deter minants within amplified region, Yamagata-lineage strains compared with B/Beijing/76/98 had three mutation points, and with B/Sichuan/379/99 had ten.Yamagata-lineage strains deleted mutation at amino acid 163(N).There was no difference of amino acid on HA1 gene high-mutable site with O or D phase feature.

  Conclusion   RT-PCR-SSCP can be applied for screening the representative strains of influenza virus.Yamagata-lineage and Victoria-lineage strains circulated alternatively in Tianjin recently, and the substitution of amino acids occurred gradually.Yamag ata-lineage strains were closely related to B/Beijing/76/98-like.